The present invention generally relates to dual in-line packagings and methods of producing the same, and more particularly to a dual in-line packaging with an improved moisture resistance and a method of producing the same.
In order to provide a desired moisture resistance, an integrated circuit packaging has a structure in which top and bottom surfaces of a substrate are covered by a resin. However, there are demands for an integrated circuit packaging with an improved moisture resistance such that the moisture resistance is maintained even when an external force is applied on terminals of the integrated circuit packaging.
FIG.1 shows a conventional dual in-line packaging 1 of an integrated circuit. The packaging 1 comprises a ceramic substrate 2, semiconductor chips 3 and 4 which are respectively mounted on top and bottom surfaces of the substrate 2, and terminals 5 and 6 which are fixed on both sides of the substrate 2. A resin layer 7 is formed on the top portion of the packaging 1 and a resin layer 8 is formed on the bottom portion of the packaging 1. These resin layers 7 and 8 are made of a glass fiber reinforced phenolic resin. The packaging 1 is mounted on a printed circuit board 9 by soldering the terminals 5 and 6 on the printed circuit board 9.
The printed circuit board 9 may warp due to heat or the like. In this case, an external force is applied on the terminals 5 (or 6) due to the warp. For example, the terminal 5 shown in FIG.2A may be pulled and bent as shown in FIG.2B by the external force. But when the terminal 5 is bent, cracks 10 may be formed in the resin layer 8 as shown in FIG.2B because the glass fiber reinforced phenolic resin is a hard material. When the cracks 10 are formed in the resin layer 8, the moisture can easily enter the inside of the packaging 1 and damage the integrated circuits. As a result, the serviceable life of the packaging 1 is shortened by the deterioration of the moisture resistance caused by the cracks 10.
On the other hand, with regard to the top surface of the packaging 1, it is conceivable to thicken the resin layer 7 to reduce the irregularities on the top surface and facilitate a printing on the top surface. However, when the thickness of the resin layer 7 is large, the contraction stress is large when the phenolic resin hardens. As a result, an active layer on the substrate 2 may separate from the substrate and the semiconductor chips 3 may float from the substrate 2.